Clayey minerals and clayey soils as possible microorganism repositories

Abstract

Clay minerals are one of the most abundant and crucial structural materials of the Earth’s crust, playing a significant role in many aspects of life. The present study aims to critically investigate the presence of microorganisms within different clayey soil samples. Microorganisms are ubiquitous by nature due to their natural ability to adapt to different habitats. Bacteria and Archea are the most abundant microorganisms in the soil and serve many important roles like nitrogen fixation. Fungi are also an integral part of the soil micro flora as they serve as food sources to other organisms as well as facilitate as layer organisms with beneficial relationships to plants. The continued evolution of man and subsequent use of clayey soils in areas such as pottery, cosmetics, engineering and geophagia brings into question whether microorganisms are harmful. Soil samples with high amounts of fine particles and colloidal substances were studied while taking into account the identified hydrated aluminosilicates and their roles in bioavailability. The study also investigated the possible types of microbial flora associated with each type of clayey soil as well as their functions within the human body. Considering the diverse origin of these microorganisms, we discuss their modes of attachment to clayey soils with the aim of minimising their transmission to humans.

Keywords:

• clay soil
• clay minerals
• microorganisms
• geophagia

ACKNOWLEDGEMENTS

The authors thank the University of Johannesburg for providing facilities used for the XRD, XRF and biological analysis.